Determining bracket locations on electronic models of teeth

ABSTRACT

Locating desired placement locations of brackets for a patient&#39;s teeth includes obtaining an array of data points from a cast of the teeth and generating a virtual model from the array of scanned data points. Individual teeth from the virtual model can be manually severed or “cut” and manually dragged from a start position to a finished position to determine a treatment plan. The orthodontist virtually marks the position on the virtual model where a physical bracket is desired. Brackets can then be automatically placed onto a cast of the teeth at corresponding positions.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 10/429,262,filed May 2, 2003, which application is a continuation-in-part ofapplication Ser. No. 10/349,559, filed Jan. 22, 2003, now U.S. Pat. No.7,347,686, which claims priority to provisional application Ser. No.60/351,311, filed Jan. 22, 2002, which applications are incorporatedherein by reference.

TECHNICAL FIELD

The invention relates generally to a method and apparatus for bracketsto be placed on patients' teeth via indirect bonding; more particularlyto a system, method and apparatus for automatically placing bracket ontodesired positions on a study cast subsequent to electronicallydetermining the bracket locations on a scanned image of the teeth; andmore particularly still an image driven system for manipulating thescanned image of teeth to a final position, and determining bracketplacement based, at least in part, on the final position of the teeth.

BACKGROUND

Dental study casts are an integral part of a dentist's understanding ofhow a patient's teeth and bite function in a static relationship. Thisstatic relationship serves three important functions. The primaryfunction is one of a diagnostic function for interpretation of anydiscrepancies or problems that exist within the bite relationship. Thesecond function is educational. For example, the study casts providebetter communication as a concrete model while helping the patientunderstand any discrepancies that may exist in the way their teethfunction in that static relationship. Third, the dental study castsserve an important medical/legal function in defining the pre-existingstatic bite relationship prior to the performance of any work. This workcan be defined either from an oral surgical standpoint, prostheticstandpoint or orthodontic/periodontal standpoint.

Yet another function is to provide a model when creating orthodonticdevices. In the prior art, impressions are taken of the patient's teethwith a study cast or model taken from the impression. It is also knownthat either the impression and/or study cast can be electronicallydigitized. For example, U.S. Pat. No. 6,217,334, commonly assigned tothe assignee of the present application describes a scanning process.U.S. Pat. No. 6,217,334 is hereby incorporated herein by reference andmade a part hereof. By digitizing the model, a set of electronic data ofthe patient's teeth and surrounding soft tissue is created which can beelectronically manipulated, displayed, stored and transmitted.

Bonding brackets to teeth for the purpose of orthodontic treatment isknown. One method of securing the brackets to the teeth comprisesmanually locating the brackets by hand. Another method involves manuallyplacing the brackets on a model of the patient's teeth, transferring thebrackets to a tray and transferring the brackets from the tray to thecorrect location on the patient's teeth. This latter method is commonlyknown as indirect bonding. While indirect bonding generally provides anaccurate location of the brackets, it does not take advantage ofadvances in the electronic imaging of teeth.

Therefore, there arises a need in the art to provide a system forproviding a scanned image set of data of a patient's teeth, displayingthe scanned image set to generate a virtual model, storing the finishpositions of the virtual model teeth after manipulation of the teethinto a final desired position, storing electronically generated bracketmarker points on the teeth of the virtual model (e.g., where thephysical brackets may be placed in order to move the physical teeth intoa final, desired position), and automatically placing brackets onto thephysical location of the marker points on a model, wherein an indirectbonding tray can be created. The present invention directly addressesand overcomes the shortcomings of the prior art.

SUMMARY

The present invention provides for an imaging and marking system forlocating the physical placement location of a plurality of brackets on apatient's study cast. In one preferred embodiment of the presentinvention, the system may include a three-dimensional scanner; acomputer including a processor, memory associated with the processor,one or more input devices, and a video display unit; and a markingdevice.

The scanner functions to gather an array of data points from theimpression and/or study cast. The computer generates a virtual model offrom the array of scanned data points. The marking device takes thelocations identified by the orthodontist from the virtual model andtransfers the data to the physical model.

After the array of data points is collected and the computer generatesan image of a virtual model, the virtual model is displayed on the videodisplay unit for the orthodontist, dentist or other medical professional(hereafter collectively referred to as “orthodontist”) to review. Eachtooth that is desired to be moved by the orthodontist in an orthodontictreatment plan may be manually severed or “cut” from the other portionsof the virtual model. Accordingly, the virtual model becomes segmentedinto a plurality of virtual model teeth, each of which may be manuallydragged with a computer input device by the orthodontist from a startingposition (e.g., that position where the tooth originally begins) to afinished position (e.g., the position that the tooth will be physicallylocated at the end of the treatment plan). The computer stores thebeginning and ending vectors of each manipulated teeth.

When each of the desired teeth have been manipulated into the desiredfinished locations, the orthodontist points and clicks with a markingtool on the position of the tooth where a physical bracket may belocated to induce the necessary forces on the tooth to move the physicaltooth from the starting position to the finished position. This point isalso stored in memory by the computer. The computer then determines thestarting positions of the plurality of teeth and may display the same.An output file of the bracket marker locations is transmitted to themarking device.

The marking device takes the output file and physically places a bracketonto a physical model with the bracket location information. Theplacement device may constitute a robotic arm which moves about thefixed model marking the known coordinates from the output file.Alternatively, the placement device may have a fixed placement deviceand move the model into engagement with the marking device or both themarking device and the model may move into engagement with one another.

Subsequent to the placement operation, the model can serve as a templateor guide to locate brackets for an indirect bonding style tray. In thismanner, the placement of brackets is improved.

While the invention will be described with respect to a preferredembodiment configuration and with respect to particular devices usedtherein, it will be understood that the invention is not to be construedas limited in any manner by either such configuration or componentsdescribed herein. Also, while the particular types of scanning devices,input devices, and marking device used in the preferred embodiment aredescribed herein, it will be understood that such particular componentsare not to be construed in a limiting manner. Instead, the functionalityof those devices should be appreciated. Further, while the preferredembodiment of the invention will be described in relation to cutting andmoving teeth in a digitized image in order to locate brackets for use inorthodontic treatments, it will be understood that the scope of theinvention is not to be so limited. The principles of the invention applyto the use of cutting, moving and marking a digitized image for lateruse in a physical model. These and other variations of the inventionwill become apparent to those skilled in the art upon a more detaileddescription of the invention.

The advantages and features which characterize the invention are pointedout with particularity in the claims annexed hereto and forming a parthereof. For a better understanding of the invention, however, referenceshould be had to the drawing which forms a part hereof and to theaccompanying descriptive matter, in which there is illustrated anddescribed a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawing, wherein like numerals represent like partsthroughout the several views:

FIG. 1 is a schematic functional block diagram of the various componentsof a system constructed in accordance with the principles of the presentinvention.

FIG. 2 is a logic flow diagram of the various steps utilized inconnection with the system of the present invention.

FIGS. 3A, 3B, and 3C illustrates the array data stored in connectionwith each of the teeth which are cut from the electronic model image.

FIG. 3D illustrates an operation flow to determine bracket markerlocations on an occluded state tooth.

FIG. 4A schematically illustrates a portion of an electronic model imageprior to moving individual teeth.

FIG. 4B schematically illustrates the electronic model image of FIG. 3Ain which a single tooth has been identified for cutting from the otherportions of the electronic model image.

FIG. 4C schematically illustrates the electronic model image of FIG. 3Bin which the teeth have been moved to the finished locations.

FIG. 4D schematically illustrates the electronic model image of FIG. 3Cin which the bracket locations have been identified and marked on theteeth in their respective finished locations.

FIG. 4E schematically illustrates the electronic model image of FIG. 3Din which the teeth have been returned to the start positions whileretaining the bracket location marking.

FIG. 5A illustrates an electronic model image of a patient's mouth inwhich individual teeth have been identified and moved locations insupport of a plan of treatment according to one embodiment of thepresent invention.

FIG. 5B illustrates an electronic model image of a patient's mouthuseful for implementing an embodiment of the present invention.

FIG. 6 illustrates an exemplary computing system useful for implementingan embodiment of the present invention.

FIGS. 7A-B illustrate horizontal processing elements determined from theelectronic model image to identify locations of individual teethaccording to an embodiment of the present invention.

FIGS. 8 a-b illustrate vertical processing elements determined from theelectronic model image to identify locations of individual teethaccording to an embodiment of the present invention.

FIG. 9 illustrates a distributed computing system for the creation anddistribution of electronic models of objects according to one embodimentof the present invention.

FIG. 10 illustrates a block diagram for an tooth location determinationprocessing system according to an embodiment of the present invention.

FIG. 11 illustrates an operational flow for determining the locations ofteeth within an electronic model image according to yet another exampleembodiment of the present invention.

DETAILED DESCRIPTION

Although the present invention will be described with respect todigitizing the model, it should be appreciated that the principles ofthe present invention may be applied to a digitized impression. In thelatter case, a computer can invert the scanned impression to provide apositive image of the patient's teeth.

Referring first to FIGS. 1 and 2, the overall method of the presentinvention is illustrated generally by the designation 20 and starts at21. First, at block 22, a dental impression of a patient's teeth andsurrounding soft tissues (hereafter referred to collectively as “teeth”for convenience) is taken. The impression material hardens, forming anegative image of the teeth. Generally lower and upper trays are used inconnection with taking the impression. Such trays are well known in theart and trays which may be used in connection with scanning animpression are described in U.S. Pat. No. 6,217,334 identified above. Abite/clutch tray is used in connection with determining the correctspatial orientation and relationship between the upper and lowerimpressions. A study cast is then formed from the impression. Theforming of the study cast is well known in the art.

At block 23, the study cast is placed in the tool or fixture 600 (bestseen in FIG. 1). The fixture 600 is used to securely hold the study castduring the scanning step. The fixture 600 may also aid the scanning stepby helping rotate the mold so that the image data can be properlygenerated.

Next at block 24, the scan of the study cast occurs. In the preferredembodiment, a dental scanner manufactured by Geodigm Corporation ofMinneapolis, Minn. may be used. The operation and scanning methodologyused by this type of line scanner is generally described in U.S. Pat.No. 6,217,334.

The output from the scanning process includes the generation of anelectronic model representing the physical representation of the scannedstudy cost. The electronic model consisting of a polygonal mesh used torepresent the seen face of the study cast. Such an electronic model maybe created using a process described in commonly assigned U.S.Provisional Patent Application, “Method and Apparatus for ComputerGeneration of Electronic Model Images” Ser. No. 60/351,270, filed Jan.27, 2002, now U.S. patent application, “Method and Apparatus forComputer Generation of Electronic Model Images” Ser. No. 10/350,302,filed Jan. 22, 2003. This application is hereby incorporated byreference.

Additionally, the electronic models may also be created using a CT Scanof an impression, rather than scanning the study cast, usingcommercially available CT scanning equipment such as a process developedby Hytec Corp. of Los Alomos, N. Mex. This process also generates aelectronic model consisting of a polygonal mesh. In both cases, thegenerated polygonal mesh is used in subsequent processing independent ofthe source of the electronic model.

At block 25 the image data is processed by processor 501. Suchprocessing may include generating an image for display at block 26 on avideo display unit 503; converting the image scan data into CNC or otherformat of output for use by a fabrication device 507 (also known as aprototyping apparatus); storing the image scan data in a memory locationor device 504; and/or transmitting the negative image scan data to aremote processor 505 via modem block 502.

In the preferred embodiment, a software package which may be used togenerate three dimensional images from the line scan data is the packageunder the designation “e-Modeler” by the assignee hereof, GeodigmCorporation. Other scanning packages such as the DataSculpt softwareavailable from Laser Design Inc. of Minneapolis, Minn. might also beused.

At block 27, the orthodontist manually segments the teeth in the virtualmodel with a CAD/CAM type “cutting” utility. This is typicallyaccomplished with a pointing tool (e.g., a mouse, trackball, pointingpen, touch pad, touch sensitive screen, etc.) or other input device 506by clicking on the point and dragging a line to initiate the cuttingfunction. The function may also be implemented in two dimensions thesame general manner by drawing a rectangle around the portion of theimage which is intended to be segmented (best seen in FIG. 4 b at 64).The orthodontist continues making cuts around each of the teeth whichare desired to be moved in the virtual image. It will be appreciatedthat the segmented virtual image teeth will generally correspond to thephysical teeth in an orthodontic treatment plan on a patient.

At block 28, the operator moves each of the now segmented teeth fromtheir start positions to their final positions. The orthodontist thenmarks the desired locations of brackets on the virtual teeth with theinput device 506. The processor 501 stores the original position data ofa tooth 60 in its start position (best seen in FIG. 3 a) in an [X Y Z 1]array in memory device 504. The finish position data of tooth 60 in itsfinish position (best seen in FIG. 3 b) is stored by the processor 501in an [X′ Y′ Z′ 1] second array in memory device 504.

The moved individual teeth 60 are then marked at block 29. The mark isdesignated by 61 (best seen in FIG. 3 b, 3 c, 4 d and 4 e) by locatingfour points on the tooth. These data points are also stored. Theprocessor maintains the position of the markers on the virtual teeth 60by storing the data points. The markers can be repositioned on the teeth60 by tracking changes to the stored arrays. For example, the locationof the bracket markers can be determined on the start position of theteeth (as shown in FIG. 3D) by multiplying the points by the inversematrix.

At block 30, the teeth are returned to the original start positions bythe processor 501, while retaining the desired location of the markers61 on the marked teeth 60. At block 31, an output file is generated toprovide the coordinate data of the marks. At block 34, the data mayoptionally be provided to an automated robotic arm to place the bracketsonto the model. However, proceeding to block 32, the marker device 508operates to create visually perceptible indicia on the physical modelwhere the brackets should be located.

At block 33, a lab can create an indirect bonding tray. The process endsat 35.

Referring more specifically to FIG. 1, the functional blocks of theelectronic components of the present invention are illustrated. Thecomponents include a computer 500 which preferably includes a processor501, a video display unit 503, a memory device 504, a user input device506 (e.g., a mouse, trackball, touch pad, touch screen and/or keypad,etc.), and a modem 502. Also illustrated is a remote computer 505, afabrication device 507, and the scanner 60 (and its attendant X-Y-Z axiscontrollers and motors).

It will be appreciated by those of skill in the art that the computer500 may be a personal computer (e.g., a Pentium based PC) or a specialpurpose computer. Further, the video display unit 503 may include anynumber of display devices such as cathode ray tubes, LCD displays, etc.Still further, the memory device 504 may include hard drives, floppydrives, magnetic tape, CD-ROM, random access memory, and read-onlymemory devices. Further, the modem 502 is illustrated to show acommunications capability. Such capability may also be by way of anetwork, etc.

The present invention includes software to place digital brackets on the3D digital dental model using six degrees of freedom. Typically thebrackets are placed onto a study cast such that an arch wire planepasses through the slots of all brackets when the teeth are in theirpost-treatment orientation. This automatic positioning may be overriddenby an operator on a per bracket basis. The software utilizes a libraryof digital brackets that can be easily extended to include allcommercially available orthodontic brackets.

As discussed above, placement device 508 takes the output file andphysically places a bracket onto a physical model with the bracketlocation information. The placement device may constitute a robotic armwhich moves about the fixed model marking the known coordinates from theoutput file. Alternatively, the placement device may have a fixedplacement device and move the model into engagement with the placementdevice or both the placement device and the model may move intoengagement with one another. In the preferred embodiment, the scanner 60may be used as the placement device 508 by locating a location on thescanner head.

In a preferred embodiment, the placement device comprises a robotic armthat automatically places the brackets onto a study cast using thebracket location information described above. In one embodiment, aBracketron robotic arm is a robotic arm developed by Alain FontenelleDDS of Bievres, France as discussed at the 2000 American Association ofOrthodontics convention, Apr. 28-May 3, 2000 in Chicago Ill. Thisrobotic arm uses the bracket location information that has been combinedwith coordinate system information of the study cost to define positionsin 3-D space where the brackets are to be located on the study cost. Inthis embodiment, software is used to extract measurements describing thelocation and orientation of digital brackets relative to anatomical anddental appliance landmarks (incisal edge, occlusal plane, arch wireplane, etc.) for the purpose of placing physical brackets on plasterstudy models using commercially available robots.

Alternatively, the bracket location information may be directly used byother robotic arm systems in which the coordinate systems of the roboticarms are consistent with the coordinate system used by the robotic arm.In this alternate embodiment, the bracket location information is useddirectly to identify the location on the study cost where the individualbrackets are to be located. Once the brackets are placed upon the studycast and secured using adhesive dispensed by a port on the robotic are,the components are used in the fabrication of the indirect bonding styletray. This fabrication of the indirect bonding style tray in independentof the method of robotic placement of the brackets onto the study castmodel. In this alternate embodiment, a method for placing physicalbrackets on plaster study models using a robot that does not rely onextracting measurements taken relative to anatomical and dentalappliance landmarks. Instead, tooling is attached to the plaster modelduring the scanning and robot placement processes that allows a commoncoordinate system to be established for use in both processes. Thecommon coordinate system makes it possible to directly map digitalbracket locations and orientations to physical bracket locations andorientations in order to direct the movements of the robot.

Fabrication device 507 may be connected directly to the computer 500 ormay be connected to a remote computer 505. The fabrication device 507may be any number of devices which can utilize computer generated dataand create a three-dimensional object from such data. One example ofsuch a machine are the devices utilizing stereo lithography technologymanufactured by 3-D Systems of Valencia, Calif. under the modeldesignations SLA-250 and SLA-500. Another example is the deviceutilizing filament technology (fused deposition modeling) manufacturedby Statasys Corporation of Minneapolis, Minn. under the modeldesignation FDM-1500.

In operation the scan data is generated by the scanner 60 and providedto the processor 501. The scan data may be saved in a memory device 504as a permanent record of the baseline condition of the patient's teeth,or temporarily prior to one of several other options. The data may betransmitted to a remote PC 505 for storage, study by a consultingdentist (or physician), or fabrication of a study cast by fabricationdevice 507. The fabrication device 507 may optionally be connecteddirectly to computer 500. These and other options may be selected by thecomputer 500 user via the input device 506.

The programming operation of the processor 501 preferably provides forscanning each of the upper and lower models and the bite registrationimpression. These scans provide the information necessary to create anelectronic equivalent of the physical study casts.

Referring to FIGS. 4 a-4 e, several schematic representations of severalteeth of the virtual image model are shown. FIG. 4 a illustrates theteeth in their start position. While several teeth are shown, only tooth60 is designated for clarity throughout FIGS. 4 a-4 e. FIG. 4 billustrates the segmenting process of tooth 60 from the other adjacentteeth in order to move tooth 60. The dotted line 64 illustrates thesegmenting or cutting tool function. Assuming that each of the teethwill be moved to accomplish the finish positions shown in FIG. 4 c, theorthodontist would use the segmenting or cutting tool on each of theteeth. However, it will be appreciated that only one or more teeth mightbe segmented for movement.

As noted above, one manner in which the teeth may be manipulated is tovirtually cut between the teeth by drawing a “cut” line between theteeth which should be separated. It will be appreciated that this isaccomplished by pointing and clicking using a separate tool in a cad/camtype library. By using these types of tools, the objects are releasedfrom their static relationship to other objects and the released objectmay be moved. Other manners of segmenting the teeth will be described inthe alternative embodiment described below.

At FIG. 4 d, the teeth in their finish positions are marked, while atFIG. 4 e, the teeth are returned to their start positions with thebracket markers remaining in the spots on the teeth which were selectedin the finish or end positions.

Alternative Embodiment

An alternative manner in which the teeth may be manipulated is nextdescribed. In this embodiment, there is provided a system, method andarticle of manufacture for automatic determination of the location ofindividual teeth within an electronic model image of a patient's mouthto allow the manipulation of the electronic model images by end users.

FIG. 5 a illustrates an electronic model image of a patient's mouth inwhich individual teeth have been identified and moved locations insupport of a plan of treatment according to one embodiment of thepresent invention. An electronic model of a patent's upper teeth areshown 101 in which individual teeth 111-113 have been electronicallymoved to allow a dental practitioner to visualize the treatment plan. Inorder for this process to occur, two events must occur. First, anelectronic model for the teeth must be generated. This occurs when aphysical mold or impression of the mouth is generated. This impressionis then electronically scanned to generate the model.

Once the electronic model has been generated for the impression, thelocations of the individual teeth need to be determined. This locationidentification may occur using manually specified locations entered intoa computing system by a user. Alternatively, these locations may beautomatically determined using information contained within theelectronic model. Once the locations of the teeth are known, theelectronic model may be cut into a set of individual teeth images111-113 that may be manipulated on a computer display device.

FIG. 5 b illustrates an electronic model image of a patient's mouthuseful for implementing an embodiment of the present invention. Theelectronic model image for a patient's mouth is typically constructedusing two model components, an upper teeth section 104 and a lower teethsection 103. Both of these teeth sections themselves include teeth modelelements, gum model elements, and a model base element. The module baseelement is added to the module when it is generated to aid in thespatial registration of the upper teeth section 104 and the lower teeth103 section relative to each other as the teeth appear in the patient'smouth. When the location of individual teeth is determined only one ofthe two teeth sections are processed at any given time.

With reference to FIG. 6, an exemplary system for implementing theinvention includes a general-purpose computing device in the form of aconventional personal computer 200, including a processor unit 202, asystem memory 204, and a system bus 206 that couples various systemcomponents including the system memory 204 to the processor unit 200.The system bus 206 may be any of several types of bus structuresincluding a memory bus or memory controller, a peripheral bus and alocal bus using any of a variety of bus architectures. The system memoryincludes read only memory (ROM) 208 and random access memory (RAM) 210.A basic input/output system 212 (BIOS), which contains basic routinesthat help transfer information between elements within the personalcomputer 200, is stored in ROM 208.

The personal computer 200 further includes a hard disk drive 212 forreading from and writing to a hard disk, a magnetic disk drive 214 forreading from or writing to a removable magnetic disk 216, and an opticaldisk drive 218 for reading from or writing to a removable optical disk219 such as a CD ROM, DVD, or other optical media. The hard disk drive212, magnetic disk drive 214, and optical disk drive 218 are connectedto the system bus 206 by a hard disk drive interface 220, a magneticdisk drive interface 222, and an optical drive interface 224,respectively. The drives and their associated computer-readable mediaprovide nonvolatile storage of computer readable instructions, datastructures, programs, and other data for the personal computer 200.

Although the exemplary environment described herein employs a hard disk,a removable magnetic disk 216, and a removable optical disk 219, othertypes of computer-readable media capable of storing data can be used inthe exemplary system. Examples of these other types of computer-readablemediums that can be used in the exemplary operating environment includemagnetic cassettes, flash memory cards, digital video disks, Bernoullicartridges, random access memories (RAMs), and read only memories(ROMs).

A number of program modules may be stored on the hard disk, magneticdisk 216, optical disk 219, ROM 208 or RAM 210, including an operatingsystem 226, one or more application programs 228, other program modules230, and program data 232. A user may enter commands and informationinto the personal computer 200 through input devices such as a keyboard234 and mouse 236 or other pointing device. Examples of other inputdevices may include a microphone, joystick, game pad, satellite dish,and scanner. These and other input devices are often connected to theprocessing unit 202 through a serial port interface 240 that is coupledto the system bus 206. Nevertheless, these input devices also may beconnected by other interfaces, such as a parallel port, game port, or auniversal serial bus (USB). A monitor 242 or other type of displaydevice is also connected to the system bus 206 via an interface, such asa video adapter 244. In addition to the monitor 242, personal computerstypically include other peripheral output devices (not shown), such asspeakers and printers.

The personal computer 200 may operate in a networked environment usinglogical connections to one or more remote computers, such as a remotecomputer 246. The remote computer 246 may be another personal computer,a server, a router, a network PC, a peer device or other common networknode, and typically includes many or all of the elements described aboverelative to the personal computer 200. The network connections include alocal area network (LAN) 248 and a wide area network (WAN) 250. Suchnetworking environments are commonplace in offices, enterprise-widecomputer networks, intranets, and the Internet.

When used in a LAN networking environment, the personal computer 200 isconnected to the local network 248 through a network interface oradapter 252. When used in a WAN networking environment, the personalcomputer 200 typically includes a modem 254 or other means forestablishing communications over the wide area network 250, such as theInternet. The modem 254, which may be internal or external, is connectedto the system bus 206 via the serial port interface 240. In a networkedenvironment, program modules depicted relative to the personal computer200, or portions thereof, may be stored in the remote memory storagedevice. It will be appreciated that the network connections shown areexemplary, and other means of establishing a communications link betweenthe computers may be used.

Additionally, the embodiments described herein are implemented aslogical operations performed by a computer. The logical operations ofthese various embodiments of the present invention are implemented (1)as a sequence of computer implemented steps or program modules runningon a computing system and/or (2) as interconnected machine modules orhardware logic within the computing system. The implementation is amatter of choice dependent on the performance requirements of thecomputing system implementing the invention. Accordingly, the logicaloperations making up the embodiments of the invention described hereincan be variously referred to as operations, steps, or modules.

FIGS. 7 a-b illustrate horizontal processing elements determined fromthe electronic model image to identify locations of individual teethaccording to an embodiment of the present invention. In order toidentify the locations of individual teeth, horizontal processing of theelectronic model image may occur. First, a horizontal plane isdetermined through the middle of the electronic model image. Thishorizontal plane is at a location between the highest most point of theimage, which would represent a point on a crown of a tooth, and themodel base element which has been added to the impression of the teeth.The resultant 2D image of the electronic model is shown in FIG. 7 a. Themodel of the teeth 301 generally follow an elliptical curve that rotatesabout a center point. The model is typically bound at either end 311,314 at points corresponding to the edge of the back two teeth, 311, 314.The separation of teeth in the middle of the model are specified usingcut lines 312 and 313 located on either side of a tooth 315. Theseparation of these two cut lines 312 313 is known to be a distancegreater than a minimum horizontal separation distance.

This minimum horizontal separation distance may be a fixed minimumnumber for all patients as all teeth are expected to be greater thansome minimum size. This minimum horizontal separation distance may alsobe a specified minimum size based upon the known size of the patient'smouth. This variation will account for scaling of minimum tooth sizesbased upon the general idea that individual patient's with larger mouthswill generally possess larger teeth. Additionally, the minimumhorizontal separation distance may also be determined by using knowledgeof the type of teeth known to exist in various portions of the mouth.For example, teeth that are expected to be located between back edge 311and cut line 312 would typically be molars. Teeth expected in the centerof the model would typically be incisors. These types of teeth are knownto possess different sizes and shapes; as such, these known differencesmay be used to vary the minimum horizontal separation distance whendetermining cut lines between teeth.

FIG. 7 b illustrates a small segment of the horizontal plane cut throughthe electronic model image. In this subset image, the model consists ofan inner image surface 321 and an outer image surface 313. An individualtooth 323 may be identified using a left cut line 331 and a right line341. The left cut line 331 may be specified by locating two end points332 and 333 in which the distance between the inner image surface 321and the outer image surface 322 are locally minimum distances. In somecases, a horizontal plane may be cut at a location in which a individualtooth is not near or touching another tooth. When this occurs theselocal minimum distances will be zero. When teeth are close or touchingeach other, the cut lines are needed to segment the teeth into separateelements in the electronic model image.

The process of looking for these locally minimum distances may beperformed at several horizontal height locations between the model baseelement and the tooth peaks. By finding cut lines at various horizontallocations, separation planes between the teeth may be specified. Thesevarious cuts should be made a locations that are centered upon the knownspacing between the model base element and the peak of the teeth. If thehorizontal cut is made close to the model base element, many teeth maybe located so close together that accurate separation of the teeth maynot be possible. If the horizontal cut is made too close to the peak ofthe teeth, features of the crowns of the teeth may be mistaken forseparation between the teeth.

FIGS. 8 a-b illustrate vertical processing elements determined from theelectronic model image to identify locations of individual teethaccording to an embodiment of the present invention. Similar to thehorizontal processing, vertical analysis of the model data may that isviewed along a vertical cut made through an elliptical arc through themodule may also permit the automatic determination of teeth separationcut lines. FIG. 8 a illustrates a sequence of teeth having variousrelation ships to neighboring teeth. Tooth 411, which is located onmodel base element 402, is shown to be completely separate from itsneighboring tooth 421. In such a situation, cut line 441 between tooth411 and tooth 421 may be easily determined by locating the local minimum452 for a vertical location along an upper surface of the model betweentooth 421 and 422. This situation is shown in more detail in FIG. 4 bwhere cut line 453 is made at the local minimum 452 between tooth 451and tooth 452. In this first situation, the local minimum 452 is easilyrecognized as a cut line as the local minimum is located at thepatient's gums and as such is located close to the model base element402.

A similar situation may arise in determining cut line 443 between tooth421 and tooth 422. In this situation, the two teeth are closer together.As a result, the two teeth touch each other at a point mid way betweenthe teeth peaks and the gum line. When this situation is compared to cutline 441, the same results shown in FIG. 8 b occur. The only differencebetween these situations is that the location of the local minimum 452will be higher than the prior case but may still be recognized if thelocal minimum is below threshold 454.

A third possible situation may arise as is illustrated by cut line 443located between tooth 431 and tooth 432. In this situation, nodiscernable separation between the two teeth are seen as they arecompletely overlapping each other. This situation occurs when the localminimum between two teeth 453 is located above a threshold 454 such thatit cannot be distinguished between local features of the teeth crowns471-472. In this situation, the cut line 443 may be determined lessaccurately by determining a point estimated to be between tooth 431 and432.

If a system combines the cut lines determined using both the horizontalelement processing shown in FIG. 7 and the vertical processing shown inFIG. 8, all of the cut lines between teeth in an electronic model imagemay be determined. When the horizontal element processing and thevertical element processing find cut lines that are identical, the cutline is know to be correct with a high degree of certainty. When a highlevel of confidence may be given to a cut line from either horizontal orvertical processing but not both, an accurate cut line may still bedetermined with a degree of certainty. Only when both horizontal andvertical processing cannot determine a location of a cut line with ahigh level of confidence must additional information be considered.

Once many of the locations of teeth are determined using just thevertical and horizontal processing described above, the locations ofother teeth may be estimated using additional information. For example,if the number of teeth known to be present is considered, the number ofteeth not found using the above process may be determined. The locationsof the known teeth may suggest regions where no known teeth were found.Using these additional pieces of information may allow the remainingpossible cut lines found in the horizontal and vertical processing to beranked to locate the most likely location in a region where teeth werenot found to propose the most likely remaining cut line locations.

FIG. 9 illustrates a distributed computing system for the creation anddistribution of electronic model images of objects according to oneembodiment of the present invention. End users operate a plurality ofdifferent computing systems 110-113 to perform their respectivecomputing tasks. End users typically use one general purpose computingsystem for a variety of tasks. In order for use of imaging systems toreplace paper and model based systems, the imaging system used by endusers 110-113 consist of laptop and desktop computing systems.

These computing systems typically possess a mechanism to communicatewith other computing systems over a communications network 101. TheInternet 101, as a publicly available communications network, providesan available communications path between virtually any two computingsystems after they first connect to the Internet. While othercommunications mechanisms exist and may be used, the Internet provides awell-known mechanism to communicate data between two computing systems.

In an image-based electronic model image system, an end user 110communicates over a communications network 101 to a server 121 toretrieve electronic eModels from a database 122. The end user 122 may belocated anywhere a connection to the communications network 101 existsto retrieve the eModels from the database 122. This database 122 may belocated within an eModel data server system 102 that is maintained bythird-parties that provide maintenance, data back-up, and similar dataprocessing overhead functions that are not an overriding concern for anend user. This data back-up, for example, may consist of long-termarchiving of data to replace maintenance of physical models that have inthe past required a great deal of effort and expense to complete.

The electronic model images themselves consist of a data file stored onthe server 121 in a database 122 that allows quick and efficient accessfor users. These electronic model images are generated in a separateelectronic model image generation system 103 that consists of one ormore model scanning units 131-134. These units 131-134 are connectedtogether using a local communications network 136 and a communicationspath 135 to the Internet 101. As such, electronic model images, oncegenerated may be transferred to the electronic model image Data serversystem 102 for ultimate use by end users 110-113.

FIG. 10 illustrates a block diagram for an tooth location determinationprocessing system according to an embodiment of the present invention. Acomputer implemented system 601 used to process electronic model imagesincludes several processing modules including a feature processingmodule 611, a model generation and acquisition module 614, a module userdisplay module 613 and a model teeth manipulation module 612. Thefeature processing module 611 itself includes a model baseidentification module 621, a model vertical feature identificationmodule 622, a model horizontal feature identification module 623, and amodule teeth identification module 624. The model generation andacquisition module 614 is used to generate and obtain electronic modelimages from remote storage for use in processing within the system 601.The module user display module 613 outputs the electronic model imagesonto a computer display device for viewing by a user of the system 601.The model teeth manipulation module 612 is used by an end user of thesystem to obtain measurements relating to the electronic model as wellas manipulate the location of teeth when a proposed treatment plan for apatient is considered as shown in FIG. 5 a.

The model base identification module 621 is used to identify the modelbase element from teeth and gum data elements obtained from within theelectronic model image. The model vertical feature identification module622 performs the processing described above with reference to FIG. 8 inwhich vertical cut lines are identified. The model horizontal featureidentification module 623 performs the processing described above withreference to FIG. 7 in which horizontal cut lines are identified. Themodule teeth identification module 624 performs the processing describedabove with reference to FIG. 8 in which vertical and horizontal cutlines are used to identify all of the teeth found within the electronicmodel image.

FIG. 11 illustrates an operational flow for determining the locations ofteeth within an electronic model image according to yet another exampleembodiment of the present invention. The processing begins 701 and anelectronic model image is obtained for use in the processing in module711. In this module, the upper teeth section or lower teeth section areselected for separate processing. Once an appropriate teeth section isselected, module 712 identifies the model base element for use ingenerating vertical and horizontal cut lines.

Module 713 generates the horizontal and vertical cut lines andidentifies single teeth that are known to be identified with a highdegree of certainty. This high degree of certainty is known when eitherof a particular vertical cut line or a particular vertical cut line hasbeen identified with a high level of confidence. This level ofconfidence may relate to a local minimum distance between horizontal cutlines being less than a specified value. Similarly, this level ofconfidence may relate to the local minimum used to define a vertical cutline being below a specified threshold. When the cut lines on both sidesof a tooth are known to a high level of certainty, the tooth may beconfidently identified.

Once some of the teeth are identified, module 714 determines the numberand spacing of the known teeth. This spacing of the teeth may identifyerrors if teeth are found to be overlapping in location or are found tobe less than a minimum size. This spacing may also be used to identifyregions of the electronic model image where teeth have yet to be found.

These regions containing possible unidentified teeth are then searchedin module 715 to identify the know vertical and horizontal structuresthat may represent addition cut lines. Using these identifiedstructures, the most likely regions where the number of unidentifiedteeth may be found. Test module 716 determines if additional teeth needto be found. If not, module 719 outputs the specification of all foundteeth and the electronic model cut planes that may be used to separatethe module into a set of separate teeth images before the processingends 702.

If test module 716 determines that additional teeth need to beidentified, module 717 identifies possible tooth separation planes inlikely regions where teeth have not still been found using thepreviously identified possible vertical and horizontal cut lines. Thepossible separation planes are ranked to find the most likely candidatein module 718. This candidate is used to identify a tooth before theregions of unidentified teeth are updated for use in further processing.Once a tooth is identified, the processing returns to test module 715 inan attempt to find additional teeth. The processing within this loopcontinues until all of the teeth are found.

FIG. 6 illustrates an example of a suitable operating environment 121 inwhich the invention may be implemented. The operating environment isonly one example of a suitable operating environment 121 and is notintended to suggest any limitation as to the scope of use orfunctionality of the invention. Other well known computing systems,environments, and/or configurations that may be suitable for use withthe invention include, but are not limited to, personal computers,server computers, held-held or laptop devices, multiprocessor systems,microprocessor-based systems, programmable consumer electronics, networkPCs, minicomputers, mainframe computers, distributed computingenvironments that include any of the above systems or devices, and thelike.

The invention may also be described in the general context ofcomputer-executable instructions, such as program modules, executed byone or more computers or other devices. Generally, program modulesinclude routines, programs, objects, components, data structures, etc.that perform particular tasks or implement particular abstract datatypes. Typically the functionality of the program modules may becombined or distributed in desired in various embodiments.

A network server 121 typically includes at least some form of computerreadable media. Computer readable media can be any available media thatcan be accessed by the network server 110. By way of example, and notlimitation, computer readable media may comprise computer storage mediaand communication media. Computer storage media includes volatile andnonvolatile, removable and non-removable media implemented in any methodor technology for storage of information such as computer readableinstructions, data structures, program modules or other data. Computerstorage media includes, but is not limited to, RAM, ROM, EEPROM, flashmemory or other memory technology, BC-ROM, digital versatile disks (DVD)or other optical storage, magnetic cassettes, magnetic tape, magneticdisk storage or other magnetic storage devices, or any other mediumwhich can be used to store the desired information and which can beaccessed by the network server 110.

Communication media typically embodies computer readable instructions,data structures, program modules or other data in a modulated datasignal such as a carrier wave or other transport mechanism and includesany information delivery media. The term “modulated data signal” means asignal that has one or more of its characteristics set or changed insuch a manner as to encode information in the signal. By way of example,and not limitation, communication media includes wired media such as awired network or direct-wired connection, and wireless media such asacoustic, RF, infrared and other wireless media. Combinations of any ofthe above should also be included within the scope of computer readablemedia.

The foregoing description of the exemplary embodiments of the inventionhas been presented for the purposes of illustration and description.They are not intended to be exhaustive or to limit the invention to theprecise forms disclosed. Many modifications and variations are possiblein light of the above teaching. It is intended that the scope of theinvention be limited not with this detailed description, but rather bythe claims appended hereto.

1. A computer implemented method of forming an indirect bonding tray,the method comprising: obtaining, at a computer including a processorand memory, an electronic model image of teeth of a patient based on acorresponding cast of the teeth, wherein the teeth of the cast arearranged in start positions; storing in the memory of the computer anarray of start coordinates representing the start positions of the teethof the electronic model image; obtaining at the computer instructions tomodify the electronic model image to move the teeth of the electronicmodel image to finish positions; storing in the memory of the computeran array of finish coordinates representing the finish positions of theteeth of the electronic model image; obtaining at the computer a firstarray of bracket coordinates representing bracket mark locations for oneor more of the teeth relative to the finish positions of the teeth; andtransforming, using the processor of the computer, the bracketcoordinates of the first array with an inverse matrix to obtain a secondarray of bracket coordinates, the bracket coordinates of the secondarray representing bracket mark locations for one or more of the teethrelative to the start positions of the teeth, the inverse matrix beinggenerated based on the stored start coordinates and stored finishcoordinates of the teeth.
 2. The method of claim 1, further comprisingdisplaying the bracket mark locations relative to the one or more teethwith the one or more teeth arranged in the start positions.
 3. Themethod of claim 1, further comprising: generating an output fileincluding the bracket coordinates of the second array; and transmittingthe output file to a marking device configured to mark the cast directlyto indicate the bracket mark locations relative to the start positions.4. The method of claim 1, further comprising marking the cast toindicate the bracket mark locations based on the bracket coordinates ofthe second array.
 5. The method of claim 4, wherein marking the cast toindicate the bracket mark locations comprises marking the cast using arobotic arm.
 6. The method of claim 4, wherein marking the cast toindicate the bracket mark locations comprises marking the cast using apen.
 7. A system for creating an indirect bonding tray, the systemcomprising: computer memory configured to store an electronic model ofteeth of a patient, start coordinates of the teeth, and finishcoordinates of the teeth, the teeth being moveable between startpositions and finish positions based on the start coordinates and finishcoordinates, the computer memory also being configured to store aninverse matrix according to which the teeth are moved between the startand finish positions; a video display unit configured to display theelectronic model of the teeth to a user; a user input device configuredto obtain first bracket mark locations for the teeth of the electronicmodel when the teeth are displayed in the respective finish positions; aprocessor configured to obtain an inverse matrix based on the start andfinish coordinates of the teeth and to calculate second bracket marklocations for the teeth when the teeth are arranged in the respectivestart positions based on the inverse matrix and based on the firstbracket mark locations for the teeth.
 8. The system of claim 7, whereinthe video display unit is configured to display the second bracket marklocations with the teeth of the electronic model arranged in the startpositions.
 9. The system of claim 7, further comprising a marking deviceconfigured to mark a cast of the teeth of the patient to indicate thesecond bracket mark locations relative to the teeth.
 10. The system ofclaim 9, further comprising: means for generating an output filerepresenting the second bracket mark locations; and means fortransmitting the output file to the marking device for directly markingthe cast with the second bracket mark locations.
 11. The system of claim9, wherein the marking device includes a robotic arm.
 12. The system ofclaim 9, wherein the marking device includes a pen.